I've heard that Weird Al is a brony, and so is Seth Green apparently. The head developer of "Naughty dog studios"{The company that made the original Crash Bandicoot and the Uncharted trilogy} is also a brony as well.

Tara Strong said on her twitter that she has info from reliable source that Tom Cruse is closed brony.
also, you may not know for him, but Luka Ivica (famous croatian snowboarder) is a brony (I know first handed since I introduced him to ponies)